Choosing the right AC switch for your application based on specification like current rating, voltage rating and triggering quadrant. Here’s an app note from STMicroelectronics to guide you on selecting the right part. Link here (PDF)
This document gives basic guidelines to select the AC switch device according to the targeted application requirements. These guidelines will allow the appropriate Triac, ACS or ACST to be selected, for most of the applications. Some very specific cases could require a higher level of expertise to ensure a reliable and efficient operation.